BIOL 300 Summer 5.3 Study Guide

Percentage of Cancers due to germ line mutations

5-10%

Percentage of Random Somatic Mutations

~90%

What does it mean to say that cancers are clonal in origin?

They start as one cell which can then divide and spread to surrounding tissues

Benign Growth

Tumors that don't spread

Cancerous Growth

Malignant growths that are able to spread.

Metastasis

The ability for cancer cells to invade other tissues

Oncogenes

Mutaged genes that cause uncontrolled growth.

Tumor-Suppressor Genes

Genes that will prevent overgrowth, mutations in this genes will lead to uncontrolled cell cycle progression.

Proto-oncogenes

Normal genes that can become oncogenes if they mutate

What is a Gain of Function of mutation

Mutation that overexpresses a gene (makes a gene work too much

3 Possible Gain of Function Mutations

Enhancer Modification, Hyperactivity within a protein, Novel Enhancer/Co-option or expressed in new tissue

Enhancer Modification

Makes more protein

Hyperactivity Mutation

Makes protein overactive

Novel Enhancer/Co-option or expressed in new tissue

Turns on in wrong place/tissue

How does a mutation in the amino acid sequence of the Ras protein contribute to cancer?

GTP gets stuck to Ras which causes cells to keep dividing due to continued activation of signal activated transcription factors

4 Primary ways that proto-oncogenes become oncogenes

Missense Mutations,

Gene Amplification,

Chromosomal Translocation,

Viral Integration

What structural change occurs in Chronic Myelogenous Leukemia (CML), and what does this give rise to?

A piece of chromosome 9 and 22 swap which causes a fused gene that is incorrectly regulated (Philadelphia Chromosome)

Explain the 2 hit hypothesis in retinoblastoma

People born with one mutation must have another mutation in early life to cause cancer

Rb

Tumor suppressor gene, it stops uncontrolled growth. Without this gene it may lead to tumors.

What do the tumor karyotypes at the end of the slides show, and how could they cause cancer?

Deletions and translocations can cause oncogenes to activate within a chromosome resulting in cancer and inactivation/disruption of tumor regulating genes.

An inherited mutation does not assure cancer, what is this called?

Incomplete Penetrance

What does the pedigree of familial breast cancer show?

It's inherited in a dominant way but with incomplete penetrance; cancer only forms if both gene copies are lost in a cell.